show Fragment on LockScreen (for Android)

activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity" >

    <Button
        android:id="@+id/show_overlay"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="show overlay" />

</LinearLayout>

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="daichan4649.lockoverlay"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="15"
        android:targetSdkVersion="17" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="daichan4649.lockoverlay.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity
            android:name="OverlayActivity"
            android:theme="@android:style/Theme.Holo.NoActionBar.Fullscreen" />

        <service android:name="OverlayService" />
    </application>

</manifest>

fragment_overlay.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    android:orientation="vertical" >

    <ImageView
        android:id="@+id/image"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/ic_launcher" />

    <Button
        android:id="@+id/close"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/btn_close" />

</LinearLayout>

MainActivity.java

package daichan4649.lockoverlay;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Button btnShowOverlay = (Button) findViewById(R.id.show_overlay);
        btnShowOverlay.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                launchOverlayService();
                finish();
            }
        });
    }

    private void launchOverlayService() {
        Intent intent = new Intent(MainActivity.this, OverlayService.class);
        startService(intent);
    }
}

OverlayActivity.java

package daichan4649.lockoverlay;

import android.app.Activity;
import android.app.Fragment;
import android.app.FragmentTransaction;
import android.os.Bundle;
import android.util.Log;
import android.view.Window;
import android.view.WindowManager;

public class OverlayActivity extends Activity {

    private static final String TAG = OverlayActivity.class.getSimpleName();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        Log.d(TAG, "[onCreate]");
        super.onCreate(savedInstanceState);

        Window window = getWindow();
        window.addFlags(WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED
                | WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);

        // fragment表示
        Fragment fragment = getFragmentManager().findFragmentByTag(FragmentType.OVERLAY.getTag());
        if (fragment == null) {
            fragment = OverlayFragment.newInstance();
        }
        FragmentTransaction ft = getFragmentManager().beginTransaction();
        ft.replace(android.R.id.content, fragment, FragmentType.OVERLAY.getTag());
        ft.commit();
    }

    private enum FragmentType {
        OVERLAY("overlay");
        private String tag;

        private FragmentType(String tag) {
            this.tag = tag;
        }

        public String getTag() {
            return tag;
        }
    }
}

OverlayFragment.java

package daichan4649.lockoverlay;

import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.Button;

public class OverlayFragment extends Fragment {

    public static OverlayFragment newInstance() {
        OverlayFragment fragment = new OverlayFragment();
        return fragment;
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_overlay, container, false);

        Button close = (Button) view.findViewById(R.id.close);
        close.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                getActivity().finish();
            }
        });

        return view;
    }
}

OverlayService.java

package daichan4649.lockoverlay;

import android.app.Service;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.IBinder;
import android.util.Log;

public class OverlayService extends Service {

    private static final String TAG = OverlayService.class.getSimpleName();

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        registerOverlayReceiver();
        return super.onStartCommand(intent, flags, startId);
    }

    @Override
    public void onDestroy() {
        unregisterOverlayReceiver();
        super.onDestroy();
    }

    private void registerOverlayReceiver() {
        IntentFilter filter = new IntentFilter();
        filter.addAction(Intent.ACTION_SCREEN_ON);
        filter.addAction(ACTION_DEBUG);
        registerReceiver(overlayReceiver, filter);
    }

    private void unregisterOverlayReceiver() {
        unregisterReceiver(overlayReceiver);
    }

    // am broadcast -a daichan4649.lockoverlay.action.DEBUG
    private static final String ACTION_DEBUG = "daichan4649.lockoverlay.action.DEBUG";

    private BroadcastReceiver overlayReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();
            Log.d(TAG, "[onReceive]" + action);
            if (action.equals(Intent.ACTION_SCREEN_ON)) {
                // ACTON_SCREEN_ON はコードからのみ登録可
                showOverlayActivity(context);
            } else if (action.equals(ACTION_DEBUG)) {
                showOverlayActivity(context);
            }
        }
    };

    private void showOverlayActivity(Context context) {
        Intent intent = new Intent(context, OverlayActivity.class);
        intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        context.startActivity(intent);
    }
}